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History of the Triple Existence
Origin of the Cosmos
the Big Bang and quarks
We start with physical existence. It has developed in uneven increments over a long period of time. This is the story.
In the beginning, there was nothing. The entire universe shot out of a very small space 13.8 billion years ago in an event known as the “Big Bang ”. A primordial explosion of immense proportions occurred as particles of incipient matter and energy shot away from each other at an incredible speed. It is hard to imagine what exploded. There were then no atoms. There were no galaxies or stars. T he ejected substance was not matter but an amorphous plasma filled with elemental particles called “quarks”. Physicist Murray Gell-Mann named them after an undefined word in James Joyce’s novel Finnegans Wake.
Quarks are building blocks of the atomic nucleus. Understood in terms of quantum mechanics, they are subatomic force-carrying particles that vibrate in waves having numerically discrete units of “ spin”. The spin tells what a particle will look like from various directions as it rotates. One type of quark, having a spin of 0, looks the same in all directions. A quark with a spin of 1 changes appearance in the middle of a rotation except that it returns to its original appearance after a full rotation. A quark with a spin of 2 looks the same after a half (180 degree) rotation . Particles having a spin of 1 /2 come back to the same appearance after two rotations. They make up all the matter in the universe. Those with spins of 0,1, and 2 create forces between particles.
Apart from spin, there are several different types of quarks differentiated by “flavor”: “up”, “down”, “strange”, “charmed”, “bottom”, and "top". Each flavor also has three colors: “red”, “green”, and “blue”. Protons and neutrons are each made of three quarks. A proton has two “up” quarks and one “down” quark. A neutron, on the other hand, has two “down” quarks, and one “up”. These are the most stable combinations although other types of quarks can be assembled in unstable structures of greater mass.
The 1/2 spin particles comprising matter are subject to the “exclusion principle” discovered by Austrian physicist Wolfgang Pauli. This principle states that two similar particles cannot exist in the same state; they cannot have both the same position and the same velocity. In practical terms, it means that matter has exclusionary boundaries. The particles cannot collapse into a state of infinite density. The same is not true of force-carrying particles. They are not subject to the exclusion principle and therefore can accumulate in very large quantities of energy.
Physicists put the force-carrying particles in four categories, sometimes called the “four forces”. Gravity, the weakest force, exerts an attraction between masses of material, even at a distance. Electromagnetism consists of electrically charged particles that either attract or repel each other. Two positively charged particles repel each other, as do two negatively charged particles. However, negatively and positively charged particles attract each other. This force is what binds protons and electrons together in atoms. The “strong attraction” force holds quarks together in protons and neutrons. It holds the atomic nucleus together. The “weak attraction” force is seen in radioactive decay.
Gravity is weaker than the other kinds of forces but has a significant impact on the universe because it involves objects of large mass interacting with each other at great distances. For example, the force of gravity holds the earth in a stable orbit around the sun. It is believed that the sun and earth exchange particles with a spin of 2 known as "gravitons” to exert the gravitational force.
The electromagnetic force is trillions of times stronger than gravity but is only effective on a small scale. This is the force that holds negatively charged electrons in an atomic structure along with the positively charged protons . It does not interact with gravitons. This force involves a polarity of charges. The attractive or repulsive force is exerted by an exchange of “photons” massless particles with a spin of 1.
The strong nuclear forceis what holds quarks together in protons and neutrons and also what holds protons and neutrons together in an atomic nucleus. It is carried in a particle with a spin of 1 called a “gluon”. The strong nuclear force has a property called “containment ” which puts particles into a structure having no color. For example , a “red” quark combined with a “ green ” and a “blue” color quark held together by gluons would produce “white”, a colorless condition . At normal energy levels , the strong nuclear force holds quarks tightly together . They tend to come a part at higher energy levels.
The weak nuclear force, responsible for radioactivity, affects matter but not particles with spins of 0, 1, and 2 such as photons and gravitons. Besides photons, this force is carried by three other spin-1 particles known as “massive vector bosons ” -W +,W-, a n dZ0. At high energy levels, these particles show similar behavior . At low energy levels, however , they behave in many different ways despite being the same type of particle.
All these particles are smaller than the shortest wave length in the electromagnetic spectrum and are therefore unable to be seen. They are difficult for laymen to understand. Subatomic particles can be observed when particle accelerators generating strong electromagnetic fields accelerate particles that are concentrated in beams and then smash them into each other, causing disintegration of their component parts. It is normally the effect of the collisions that can be observed.
Modern physics is built upon a foundation of mathematical equations supported by experimentation with specialized equipment. Often the theory comes first and is followed by the confirming experiment. For example, the Higgs boson, which allows particles to assume mass, was predicted in the 1960s but it was only recently verified.
events of the first three minutes
At any rate, the cosmic soup originally consisted of these rather mysterious particles called “quarks”. Realize that, at the beginning of existence, matter had not yet separated from energy. Neither truly existed. In the first split second of creation we had only the subatomic particles. The primordial plasma was heated to a temperature of more than one trillion degrees Celsius. What came next is truly remarkable. The universe began to expand. It expanded rapidly in an unbelievably short period of time. This was the Big Bang.
It is believed that within 10-43 seconds, gravity emerged as a separate force. (This is one ten millionth of a trillionth of a trillionth of a trillionth of a second.) The gravitational particles appeared. Around 10-34 seconds into the creation, matter appeared in the form of quarks and electrons. Antimatter simultaneously appeared. The “strong force” split from the “electroweak” force, releasing a large amount of energy . Then, around 10-10 seconds after the Big Bang, there was a split between the “electromagnetic force”and the “weak force ”. There were now four forces: gravity , the strong force, the weak force, and the electromagnetic force.
But there was more. Around 10-5 seconds after the beginning, quarks combined to form protons and neutrons. Anti-quarks, their counterparts in anti-matter, formed anti-protons, which are protons having a negative charge. The protons and anti -protons collided. As their respective masses were extinguished, photons of energy were released. How ever, there were slightly more protons than anti -protons - perhaps one part in a billion more . That meant that after the mutual annihilation some protons remained . It was those that make up the nuclei of matter in our universe.
A similar process took place with respect to electrons and positrons, which are electrons with a positive charge. These particles also collided and annihilated each other. As in the case with protons, there were slightly more electrons than positrons so that only electrons existed after the mutual annihilation. At the end of the process, after the particles of opposite charge were paired off and annihilated, only protons, electrons, neutrons, and photons of energy remained. All this happened within a very short time. Around three minutes after the Big Bang, most of the surviving quarks had taken the form of protons and neutrons in hydrogen or helium nuclei.
The next phase of activity took place in the next 380,000 years. This is the third part of our story. Here we see the formation of atoms as negatively charged electrons became paired with positively charged protons. The fourth part of the story of cosmic creation is what has happened in the remaining 13.7 billion years.
The word “story” is applied loosely to this situation. Stories describe events that take place in time and space often involving human beings. There were, of course, no humans when the universe was created. Space and time did not exist in a recognizable form. Therefore, there was no “place” for events to occur.
If there were events in the story, they would have had to involve objects moving about in space. Two types of being filled this early universe: energy and matter. Matter we see as something that fills space. It has spatial boundaries marking its territory. Energy, in contrast, would be what allows matter to move from one place to another. Energy and matter would jointly create a particular set of events.
At this point, however, the universe was contained in an infinitesimal volume of space. Energy and matter were fused in a plasmic mass. The physics of Albert Einstein holds that matter is convertible into energy, and vice versa, according to the formula e = mc².
Einstein’s theory of relativity contemplates that both time and space can be bent. Space bends around large structures of matter that exert gravity. The perception of time changes with an observer’s motion. In short, the traditional framework of storytelling breaks down under extreme conditions.
We tend to think of space as a realm of limitless expanse. But space does not exist without matter. Modern physics regards space as a medium that expands with content. The general theory of relativity holds that gravity represents space being bent in the presence of matter.
Physicists like to say that “matter tells space how to bend and space tells matter how to move.” According to this view, matter would not be “exploding out into space” after the Big Bang but moving apart from other matter with the expansion of space. In that period, space would be inflating like a balloon so that its volume would be proportionate to the matter contained.
the age of radiation
Einstein's physics is relevant to events happening at the start of creation. We did not have objects moving about in space in orderly ways as Isaac Newton's equations prescribe. Instead, the raw elements of the physical universe were colliding with each other. Energy was embodied in photons vibrating at certain frequencies and wave lengths that traveled at the speed of light. Matter was embodied in neutronsand protonsand electrons. Meanwhile, the universe was rapidly expanding.
A proton is positively charged. A neutron has no electromagnetic charge because each neutron contains a positively charged proton and a negatively charged electron that offset each other. Protons and neutrons form the nucleus of an atom, which is positively charged . Negatively charged electrons surround them in the same number as in its electromagnetic charge. The simplest and most plentiful element , hydrogen , contains a single proton and a single electron.
Energy is harder to explain. We think of this as motion, heat, or light, but energy is also associated with massless particles called “photons” having a spin of 1. These photons vibrate at certain frequencies and travel through space in waves of particular length. Greater frequency of vibration is associated with more heat. The primordial plasma was once very hot but it has cooled considerably as the universe expanded.
At the time of the Big Bang, the universe was an amalgam of energy and matter compressed into a very small space. For thousands of years, photons spontaneously changed into matter. Matter freely changed back into photons. Matter and energy were mixed together in the primordial soup. Einstein's equation describes the quantitative relationship between matter and energy as they become converted into each other. This process of conversion has been compared to steam condensing into water and water freezing to become ice.
As the universe expanded, the wave length of the photons increased so that a cooling process took place. The radiation could then not so easily be converted into matter. Energy converted into matter made equal quantities of protons and neutrons along with free electrons. Neutrons each have a proton and electron. However, free-standing neutrons are unstable; they have a half-life of 887.5 seconds. Many broke down into protons and electrons.
Some neutrons survived in combination with protons. A single proton and neutron fused together forms deuterium (²H), which is the nucleus of a heavy-hydrogen atom. Several deuterium nuclei collided with free-floating protons to produce helium nuclei (consisting of two protons plus one or two neutrons). In a few cases, helium nuclei collided with protons to produce nuclei of lithium (three protons plus three or four neutrons) which were unstable.
The nuclei of deuterium atoms started to form when the temperature had dropped to around 3 billion degrees Celsius but they were soon knocked apart in particle collisions. By then , the proportion of neutrons had dropped to around 14 percent of all matter . When the temperature had dropped to 1 billion degrees, the ra diation was insufficient to destroy the deuterium nuclei. In the next few seconds, most of the remaining neutrons were combined with protons to produce nuclei of helium-4, each consisting of two protons and two neu trons. Helium -4 nuclei are stable.
Afterwards, the nuclei of hydrogen, helium, and, in a few cases, lithium combined with free-floating electrons to form electrically neutral atoms. These became the elemental building blocks of matter. But there was a catch. Each time an atom was created, a photon of energy was released. The surplus photons collided with electrons that had not been captured in atoms. The two types of energy particles, mixed together, moved at the same temperature in mutual interference.
A kind of stalemate ensued. The free-floating photons collided with atoms, knocking out their electrons which became free once again. The positively-charged nuclei of these atoms then picked up other electrons. With the recombination of atoms, photons were again released. They then reacted with other electrically neutral atoms, perpetuating the cycle.
And so it went for the first 380,000 years. The photons of energy and electrons of matter interfered with each other’s development. This was because the universe was still hot. It consisted of white-hot particles of matter in a sea of photons. Energy and matter could not escape each other’s clutches.
After around 380,000 years, however, the universe had expanded to the point that its temperature dropped to below 3,000 degrees Kelvin. The increased wave length of the photons generated insufficient energy to ionize the hydrogen atoms. Those atoms remained intact. Matter and energy went their separate ways.
What happened then was that the previously formed nuclei combined with electrons to create atoms. The electrons, now locked in atoms, could no longer interfere with the photons of light so that the latter could now travel unimpeded through space. The electrically neutral atoms which balanced the positively and negatively charged particles no longer blocked the transmission of light. The photons were then able to move through a clear universe.
That is why astronomers can detect radiation emitted after universe had cooled to a sufficient point (3000 degrees Kelvin) but no earlier: Light was not then able to escape. This energy exists today in the form of cosmic background radiation. The level of radiation, while slowly decreasing, is much the same no matter where one looks in the night sky. Its temperature is around 2.7 degrees above absolute zero.
Prior to their separation, the mass density of energy exceeded that of matter. The universe was dominated by the dynamics of energy. Subsequently, it has been dominated by matter. Matter exists mostly in the form of hydrogen atoms; helium accounts for about 25 percent of its mass. Atoms of these two elements along with energy waves floated out through space as the universe expanded.
The Human Species Appears
a search for our ancestors
We who contemplate Big History are human beings. We belong to that species of animal life called Homo sapiens. But Homo sapiens did not always exist. This species, too, has a creation story.
How did human beings develop? A theory that stirred controversy in the 19th century but has since become generally accepted within the scientific community is that mankind evolved from other species of life including apes, reptiles, and even primitive single-cell organisms. It is not that such creatures living today are our ancestors but that back in time, millions of years ago, there were living organisms similar to them whose descendants we are.
The human species evolved from reptile and mammal groups. Our backbones, brains, eyes, legs, teeth and other bodily organs were derived from reptilian species dating back 300 million years. The first mammals, which were synapsid reptiles, appeared around 210 million years ago in the late Triassic period. This class of animals is known for having hair, being warm-blooded, giving birth after a period of gestation within the mother’s body, and feeding its offspring with milk from the mother.
The primate order of mammals arose in the Cretaceous period between 60 and 80 million years ago. These included monkeys and apes. Our distant forbearers were hairy creatures with powerful forearms and tails that swung through the trees. Such creatures branched off into several different families over eons of time. Our species came from one of those families many years ago.
Paleontologists used to look for aa “missing link” that would connect mankind with monkeys and apes. This approach is now thought to be simplistic. There is not just one “link” between ourselves and other primates but an uncertain ,complicated line of ancestors whose pedigrees are based on incomplete records.
There is no current species of monkey or ape from which humanity is descended. Rather, we must look to the fossil record from millions of years ago to find our and the apes’ common ancestors. In its various branches, the tree of life includes now-extinct primates that led directly to us as well as to primates with currently living descendants , both human and non -human . Ultimately , this record extends back to the beginning of life.
What we know about humanity’s ancestors comes mostly from fossils discovered in the ground. Often they are particles of bone mixed with other materials. Paleontologists must try to assemble the bone fragments into a complete skeleton. From the structure of a skull or other skeletal fragment, they must then identify a species. Typically a newly discovered species is given a Latin-sounding name by the person who discovered it.
The story in this chapter is therefore a detective story that depends mainly on the evidence left behind when representatives of the pre-human animals died.
During the 19th century, paleontologists amazed the world by unearthing dinosaur bones. There were also discoveries of bones belonging to creatures that resembled contemporary human beings to one degree or another. The skeletal remains could be dated by radiocarbonThe human species appears
the story of humanity’s development as a species of life starts to emerge.
Scientists know what the skeleton of a modern human being looks like. They are also familiar with the skeletons of apes, monkeys, orangutans , and other primates . Sometimes a skeleton was found with features from both groups . Was this a direct ancestor of our species? In the 20th century , it became an obsession to trace the lineage of modern humans back to earlier species.
Tell-tale signs in a fossil indicate how far along the path toward humanity it has gone. Homo sapiens has, among other features, a leg structure suitable to standing upright, manual dexterity, meat-eating tendencies, lack of a tail, lack of a fur coat, eyes facing forward , snouts, large and a larger cranial cavity including a capacity for language . Being relatively intelligent , our species also has the ability to fashion tools. Sometimes stone tools or fragments are found near skeletons, helping to determine what the species is.
In recent decades, evolutionary progress is also determined by DNA testing. This is a more powerful and precise technique than bone analysis but, at the same time, it is rather too technical to support stories of human evolution. Therefore, this chapter will focus on the efforts of paleontologists to trace our species’ ancestry back to more primitive forms of life through the skeletal remains that have been unearthed in various places and times.
our primate relatives
Mammals are a class of animals in the phylum of Chordata, which includes backboned animals. They are warm-blooded, furry creatures which carry offspring within their mother’s body and which then feed them externally for a time. This type of creature first evolved in the age
of reptiles 180 million years ago. It began to radiate after the demise of the dinosaurs 65 million years ago.
Within the mammal class lies the order of primates. Such animals have hands capable of grasping small objects. There is bare skin on the finger tips and underside of the hand with a pattern of ridges unique to individuals. Primates have nails at the end of their fingers instead of claws, and forward-looking eyes inside bony eye sockets that allow the creature to form a three-dimensional image of visual scenes. Their snouts are typically shorter than those of other mammals, suggesting that the sense of smell is less developed. Most primates live in trees. Many are small nocturnal animals that scavenge for insects beneath the bark. Four out of five species of primates live in tropical rain forests.
A group of primate-related mammals called Plesiadapiformes inhabited parts of Europe and North America during the early Paleocene period, around 60 million years ago. These were small insect-eating animals that lived in trees. Having long snouts and broad skulls, they looked like tree shrews or rats. Such creatures had claws rather than nails. Their eyes did not face forward. Their toth structure indicates a variety of diets.
Somewhat later, between 35 and 54 million years ago, there appeared two families of euprimates, omomyids and adapiforms, that are more clearly related to primates. Omomyids are known for their large eyes and night-seeing ability. Weighing between 2 ounces and 2.5 pounds, they were slightly smaller than adapids, which are ancestors of the contemporary lemurs of Madagascar. Both types of species had nails, forward-looking eyes, large snouts, and relatively large brains. Both were tree-dwellers inhabiting territories in Europe and North America during the relatively warm Eocene period when those two areas were connected by an Arctic land mass.
The early primate-like mammals are called “hominoid primates”. Paleontologists place them in two categories: Hominoidea and Hylo batidae. The latter include the gibbons and siamangs of southeast Asia. These “lesser apes” weigh about 15 pounds, chatter loudly, and have long arms useful for swinging through tree branches. The Hominoidea family comprises two sub-families: Ponginae and Homininae. The Ponginae include orangutans and an extinct ancestor from the Miocene period, Sivapihecus. The Homininae include the African great apes and human beings.
Modern-day primates include, besides mankind, many other species. The three main groups are called prosimians, monkeys, and hominoids. The prosimians include lemurs, lorises, and bush babies. The monkeys include what we call monkeys of both the Old and New Worlds, including
baboons. Hominoids include the great apes and man. The smaller prosimians evolved first. The monkeys were larger; the hominoids larger still. The mouse lemur weighs two ounces. Male mountain gorillas average 350 pounds.
The so-called “higher primates”, or “anthropoids”, include monkeys, apes, and man. Their common ancestor may have been a creature known as “Aegyptopithecus ” whose fossils have been found in the Fayum Depression sixty miles southwest of Cairo, Egypt. Its skeletal remains suggest that this creature was about the size of a fox and roamed on all fours through the tree tops. The male of the species was twice the size of the female. Its size and behavior most closely resembles monkeys. Aegyptopithecus lived about thirty-five million years ago when monkeys began to diverge from apes in the evolutionary process.
Twenty million years ago, at the start of the Miocene age, average temperatures on the earth’s surface dropped by an estimated ten degrees Fahrenheit. As the polar ice caps expanded, the tropical jungle shrank into a region near the Equator. Continental drift shoved Africa into the Eurasian continent. Such changes created both an ecological crisis and an opportunity for animals such as primates living in the African jungle. Dozens of ape species existed then. They had adapted variously to their different environments. Which, if any, was the ancestor of man?
In attempting to classify the fossil remains of hominoids of that period, two paleontologists at Yale, David Pilbeam and Elwyn Simon, wrote that during the early Miocene Age, “three separate species of a genus called Dryopithecus were living which were most probably ancestral to the chimpanzee, the gorilla, and the orangutan.” They believed that the ape and human species had already split by then. This was perhaps thirty million years ago.
More recent evidence suggests, on the other hand, that the split likely occurred around five million years ago. When two researchers, Allan Wilson and Vincent Sarich, at the University of California at Berkeley examined and compared the blood protein of primate species, they found that chimpanzees, gorillas, and human beings were more closely related to each other than to the orangutan. The degree of molecular variation also indicated the speed at which the various species had diverged. The three species all originated in Africa.
If one assumes that genetic mutations occur randomly at a certain rate, it is estimated that the Old World monkeys branched off from the homininae species between 25 and 34 million years ago. The gibbons separated from the great apes and humans about 18 million years ago; and orangutans, about 12 million years ago. Gorillas split from humans and chimpanzees 8 million years ago; and chimpanzees from humans, 5 to 7 million years ago.
Chimpanzees and gorillas live in equatorial Africa. Both spend much of their time on the ground where they walk on all fours, using their knuckles to support the body. Yet, both species are also tree climbers. Chimpanzees live in extended families where both males and females are hierarchically organized. They are able to use simple tools . Gorillas live in small male-dominant communities. Their diet consists of tree foliage, mainly bamboo . Their physical size is similar to that of human beings.
With respect to the great apes, human beings share 97.7 percent of their DNA with gorillas and 98.4 percent of their DNA with chimpanzees. This evidence suggests that the split from chimpanzees occurred quite recently. A pigmy chimpanzee of central Africa known as “bonobo” is humanity’s closest living relative in the ape family.
There is a theory that as a new species evolves from a group, it resembles the juvenile members of the group from which it has diverged more than the adult members. If that is true, human beings would most closely resemble juvenile chimpanzees. The new species could “radiate”, or increase quite quickly in population, if it fills a niche resulting from change in environmental conditions.
Paleontologists believe that the human species lost its tail around 25 million years ago. Eye sockets enclosed in the skull (post-orbital closure) developed around 40 million years ago. The modern ape (and human) tooth pattern appeared 35 million years ago; the ability to rotate the thumb, 18 million years ago; the stable elbow structure, 15 million years ago.
More recent developments, peculiar to the human species, include the broad sacrum (a triangular bone at the base of the spine above the pelvic cavity) which first appeared 3.5 million years ago; the human knee joint and foot, which appeared 1.8 million years ago; and the high forehead of the skull, which appeared 100,000 years ago.
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